1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) apparatus and its manufacturing method.
2. Description of the Related Art
Generally, an LCD apparatus is constructed by a transparent insulating substrate on which: thin film transistors, pixel electrodes and the like are formed, and a counter transparent insulating substrate (counter substrate) on which a counter electrode is formed. In this case, the voltage at the counter electrode should be maintained at a predetermined value.
In a first prior art LCD apparatus (see JP-A-2-220031 and JP-A-4-153626), in order to apply a voltage to the counter electrode, transfer electrodes are provided on two or four edges of the transparent insulating substrate. The counter electrode is in contact with the transfer electrodes by paste including conductive spacers. This will be explained later in detail.
In the above-described first prior art LCD apparatus, however, since the number of the transfer electrodes is limited, the resistance between the transfer electrodes and the counter electrode is so large that the voltage at the counter electrode cannot be maintained at a predetermined value. Also, since the diameter of sealing peripheral spacers is about the same as that of the conductive spacers while the gap for the sealing peripheral spacers is different from the gap for the conductive spacers, stress may be generated so that irregular display occurs, thus degrading the display quality. Further, since the sealing peripheral spacers press data bus lines as well as scan bus lines, the data bus lines and the scan bus lines may be disconnected. Additionally, since a step for coating seal material is different from a step for coating the paste including conductive spacers, the manufacturing cost may be increased.
In a second prior art LCD apparatus (se e JP-A-8-262484), an auxiliary line also serves as means for applying a voltage to a counter electrode via a columnar spacer. That is, in order to electrically connect the auxiliary line to the counter electrode, the columnar spacer formed by color filter layers is provided at pixels. This also will be explained later in detail.
In the above-described second prior art LCD apparatus, since a voltage is applied from a large number of location to the counter electrode, the resistance between the auxiliary line and the counter electrode is so small that the voltage at the counter electrode can be surely maintained at a predetermined value. Also, since no stress is generated, irregular display may not occur, thus improving the display quality. Further, the data bus lines and the scan bus lines may not be disconnected. Additionally, since a step for dispersing display spacers is unnecessary, the manufacturing cost can be decreased.
In the above-described second prior art LCD apparatus, however, if the counter electrode is a little oxidized or contaminated by insulating material, the counter electrode is no t always in contact with the auxiliary line, so that the electrical connection therebetween is unstable, particularly when vibration or impact is applied to the LCD apparatus.
It is an object of the present invention to provide an LCD apparatus and its manufacturing method, capable of stably and remarkably decreasing the resistance between a counter electrode and a transfer electrode.
According to the present invention, in an LCD apparatus, a transfer electrode is formed on a first insulating substrate, and a columnar spacer and a counter insulating substrate, and a columnar spacer and a counter electrode are formed on a second insulating substrate. A sealing element formed by seal material and conductive spacers adheres and seals the first and second insulating substrates, so that the counter electrode is in contact with the transfer electrode through the conductive spacers.
Also, in a method for manufacturing an LCD apparatus, a transfer electrode is formed on a first insulating substrate, a first columnar spacer and electrode a counter are formed on a second insulating substrate. Then, seal material including conductive spacers is coated on a periphery of at least one of the first and second insulating substrates. Then, the first and second insulating substrates are adhered, so that the counter electrode is in contact with the transfer electrode through the conductive spacers.